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srn4 - n/a
30-Mar-06, 10:13 AM
Is it a bad idea to run the drive system (HTD pulleys and belt) without the fan attached.



I want to do this to allow me to check the drive system for vibration before risking sticking the fan on it.



My concern was that, with no load the belt will slap about like crazy and cause damage



Any thoughts?



Dunc

Michel - n/a
30-Mar-06, 09:16 PM
NO !

If you have a rev limiter, you can , but you must keep in mind that 90 % of vibrations come from prop. You' ll have more belt flapping if prop is not in place , because blades act like a tenser on one side of belt.

srn4 - n/a
31-Mar-06, 04:10 PM
Well I ran the drive system with no load and all seemed ok, so I hooked up the fan and it seems to work...lord only knows how long it will be before fatigue causes something to fly off http://hovercraft.org.uk/images/icons/smiley_icons/icon_twisted.gif http://hovercraft.org.uk/images/icons/smiley_icons/icon_rolleyes.gif



Now all I need is my skirt and we can see if the thing will actualy hover http://hovercraft.org.uk/images/icons/smiley_icons/icon_eek.gif scary stuff!

Mart366 - n/a
31-Mar-06, 05:11 PM
Dunc,



why do you do things that people advise you not to do ??





and if i recall this isnt the first time you did this, you posted the same about your rotax engine in your other hov, and were advised against it, yet still did it...





if you dont want to heed any advice, why ask??





Mart http://hovercraft.org.uk/images/icons/smiley_icons/icon_confused.gif

srn4 - n/a
31-Mar-06, 07:08 PM
Hu???



My question was



"Is it a bad idea to run the drive system (HTD pulleys and belt) without the fan attached"



And the answer was "no"





Am I just being dumb and not understanding peoples answers.... http://hovercraft.org.uk/images/icons/smiley_icons/icon_confused.gif

Michel - n/a
31-Mar-06, 10:39 PM
Other' s advises are like barriers,

Herb is greener on the other side.

I told you it was not a good idea, due to risks of failure, but "risk" does ' nt mean it will break at any try.

Some engines have a breakable part determined to save either the whole engine or the device to which it' s tied, in case of over rev.

For example, my Kohler has a rev regulator, the first thing we do when used in hovercraft is remove it, and use propeller as rev regulator. This allows us to make engine turn at 3900 r/mn in place of 3300 in case of need. But crankshaft normally will break between 4 and 5000 r/mn.

Most of 2- strokes engines do not fear over rev, but who knows " if " or " when " it will leave you.